Collector for dynamos and the like and process for making such collectors



Jan. 9, 1923. 1,441,569.

0. F I S C H E H.

COLLECTOR FOR DYNAMOS AND THE LIKE AND PROCESS FOR MAKING SUCH COLLECTORS.

FILED AU G. 12. 1921 IAN/ENTIJ 0770 Fun/ER a\/ ATT'D N 5W5 c, MM Mag Patented J an. 9, 1923.

UNITED STATES PATENT oFHca.

OTTO FISCHER, OF STUTTGABT GEBHANY, AS SIGNOR T ROBERT BOSCH AKTIEN- GESELLSCHAIT, OI STUTTGABT, GERMANY.

COLLECTOR FOB DYNAMICS ANDJHE' LIKE ANDTBOCESS FOR MAKING SUCH COLLECTORS.

Application filed Augult 12, 1921. Serial N0. 491,851.

To all whom it ma concern:

Be it known that O'rro. FISCHER, Gernian subject, residing at Stuttgart,'Germany, have invented certain new and useful Improvements in Collectors for Dynamos and the like and Processes for Making SuchCollectors (for which patents have been ap lied for in Germany, application filed April 29, 1919; Holland, April 24, 1920; Sweden, June 10 14, .1920; Switzerland tria, June 14, 1920; zecho-slovakla, June 16, 1920; Italy, June 22, 1920; Great Britaln, June 22, 1920 Belgium, July 2, 1920 France,

July 9, 1920), of which the following is a 15. specification.

The invention relates to the manufacture of collectors (for dynamos, motors, etc.) with bushings consisting of an insulating substance such as porcelain, steatite,bakelite or the like upon which the copper segments are formed'by a galvanic precipitation process. The general idea of producing segments through galvanic deposits is known and the practical procedure hitherto consisted in covering the collector bushing with a layer of enamel and in thereupon applying protochloride of-gold to the surfaces that were to receive the conducting segments, this gold then being fixed, by annealing. The surfaces thus covered with protochloride of gold were then thickened in an electrolytic bath by galvanic deposits.

In comparison with this known collector producing process the new process according to the invention is much simpler. It enables the collectors to be made quicker and cheaper and with segments with well defined borders, p,

bushing is either a kind .of insulating substance such as bakelite that can be worked which was not possible with the old process.

A special coating of enamel is not neces- 40 sary with the process according to the invention, and the segments need not be pre pared for the subsequent electrolytic bath by applying a special covering of protochloride of'gold for each individual segment.

An important feature of the invention consists in covering, by a galvanic or other process, the entire periphery of the body of the collector, which is made of a suitable insulating substance, with a coating of metal June 12, 1920; Aus

and in forming the various segments by cuttlng up the lntegral copper coating with a saw. The collector segments thus produced are separated by well definedga s and the rough edges formed at the gaps y the saw afford a safeguard a ainst lateral movements of the segments. urther security against lateral movement may be provided in the shape of grooves formed upon the circumference of thecollector bushing. The galvanic coating preferably extends so far over the collector bushing that it embraces the bushing at the ends and is thus safeguarded against the action of the centrifugal force set up when the collector rotates. If the collector bushing is made of bakelite or any other substance that can be worked by tools, the segments can be produced without any further measures by cutting up the integral copper coating with a saw. But if (toobtain a great resistivity to heat) steatite or some other ceramic substance is employed, grooves are formed in the substance previous to the baking of the same and while it is still soft, in order to render it possible to cut up .the subsequently deposited copper coating without the saw being damaged by the hard baked steatite substance.

In the drawing a constructional form of collector made in accordance with the invention is shown.

gig. 1 representing alongitudinal section, an

Fig. 2 an end view ofthe collector or commutator.

The material used for the collector body or by tools or, if it is to be capable of resisting high temperatures, a ceramic substance, such as st'eatite, porcelain or the like, is employed, which is shaped as required before baking, due allowance being made for shrinkage.

If bakelite is used for the core of the collector bushing, the latter is finished on' 'a lathe-with the exception the grooves b that are afterwards make with a saw-and the whole periphery and inwardly extending latof copper is deposited upon the 'graphited surface. The copper coating of the brush surface of the collector is preferably made thicker than the lateral gripping coatings, this being accomplished by applying a coating of varnish or the like to the side surfaces (as soon as they have become thick enough to securely hold the segments in place) and by subsequently continuing the galvanic process until a sufficient thickness of the brush surface of the collector is attained. To ob tain a smooth surface the integral copper coating is then shaved in a lathe andthen subdivided into the required number of seg-* ments by cutting deep grooves b with a saw. In order to prevent copper. or graphite particles from accumulating in the grooves these latter are filled with cement or some kind of special insulating substance capable of resisting heat. The shallow rooves c in the lugs of the segments are also made with a saw or cutter, but only deep enough to allow the wires of the armature to be conveniently soldered to them.

But if the substance used for the collector bushing is steatite, porcelain or another ceramic material, deep grooves b for separating the segments, and shallow grooves c for fixing the armature wires are formed in the bushing whilst it is still soft. The bushing is then baked, due allowance being made for shrinkage. The deep grooves are then filled with ordinary putty so as to prevent the depositing of copper therein during thegalvanizing process. It is not absolutely necessary to fill the grooves b with cement or the like, but this is the preferred Procedure because if this were not done it would afterwards be necessary to carefully remove with a file or the like any layer of copper that might have been formed during the electrolytic process.

After an integral coating of copper has been deposited on the bushing, and when the surface of this coating has been shaved smooth with a turning tool as described,

- the copper deposit is cut upat the grooves b and c-with a saw, which also removes the filling substance from the grooves. By thus providing grooves in the steatite previous to the baking process, the copper coating can be completely out into segments with a saw or cutter without the tool being damaged by the hard steatite.

It is obvious that the new process may also be used for producing current distributing disks, switch plates, etc. To make the collector fit exactly on the armature shaft its bore may be provided with a metal bush-' ing. A sleeve of glazed cardboard may be inserted between the metal and the steatite bushings. To obtain copper segments that are very securely fixed on the ceramic bushing a covering of protochloride of gold which is fixed by annealing may be used instead of th coating of graphite. The coating of copper might also be put on by the Schoop squirting process or in any other way without departing from the spirit of the invention, but the copper deposited by a gal-. vanic process is specially adapted for collectors on account of its hardness.

{The term collectors in the following claims is intended to cover all similar contrivances used for commutating or distributing electric currents, etc.

I claim:

1. A process of producing collectors consisting in forming the body of the collector of a suitable insulating substance, in covering the surface of the body with an integral metallic coating, and in subsequently forming metallic segments by cutting up the coating.

2. A process of producing collectors consisting in forming the body of the collector of a suitable insulating bushing, in covering the periphery of the bushing with an integral metallic coating, and in subsequently forming metallic segments by cutting up the coating with a saw.

3. A process of producing collectors consisting in forming the body of the collector of a bushing of soft ceramic substance, dividing the periphery of the soft bushing into segments by making grooves in the periphery, hardening the soft bushing by baking it, covering the entire periphery with an integral metallic coating, and in finally cutting up the integral metallic coating at the said grooves so as to form metallic segments.

4:. A process of producing collectors consisting in forming the body of the collector of a bushing of soft ceramic substance, di-

viding the periphery of the soft bushing into segments by making grooves in the periphery. hardening the soft bushing by baking it, filling the grooves'with a plastic substance, covering the entire periphery with an integral metallic coating, and in finally sawing up the integral metallic coating at the said grooves so as to form metallic segments and remove the plastic substance.

5. In a collector made by the process claimed in claim 1, inwardly-projecting lateral surfaces at the ends of the bushing, and inwardly-projecting extensions of the metallic segments engaging with the said inwardly-projecting lateral surfaces, whereby the segments are prevented from being dislodged by centrifugal force.

6. In a collector made by the process claimed in claim 1, inwardly-projecting lateral surfaces at the ends of the bushing, in- 130 wardly-projecting extensions of the metallic In testimony whereof I have afiixed my segments engaging with the said inwardlysignature in presence of two Witnesses. projecting lateral surfaces, a peripheral groove in the said bushing, and an inward OTTO FISCHER bulge in each segment engaging with the Witnesses: said groove, whereby the segments are pre- ALFRED MEYER, vented from being dislodged. HELMA PANDER. 

